Multi-chip press-connected type semiconductor device

ABSTRACT

A multi-chip press-connected type semiconductor device comprises: a plurality of active element chips to control an electric current flowing in one direction; a plurality of diode chips that transmit the current in a direction opposite to the current transmitting direction of said active element chip; and electrode plates for said active element chip and for said diode chip, said electrode plates pressing from above and under with said plurality of active element chips and said plurality of diode chips being interposed therebetween; wherein said diode chips are disposed in all of outermost peripheral chip positions with no-existence of other chips adjacent to at least one side of a chip in a chip disposing region, and are disposed in internal layout positions surrounded with the outermost peripheral chip positions, and said diode chips to be disposed in the internal layout positions are arranged in order of a total number of other chips from the smallest that exist adjacently to at least one of a side and a vertex of a chip.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2003-304381, filed on Aug. 28,2003; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to a press-connected typesemiconductor device, and more particularly to a multi-chippress-connected type semiconductor device including a plurality ofsemiconductor chips.

An IGBT defined as a MOS gate drive type switching device is widelyemployed as one of semiconductor devices for power control, and an FRD(fast recovery diode) mix-mounted IGBT serving to make full use of thecharacteristic thereof is known as one example of a multi-chippress-connected type semiconductor device.

The multi-chip press-connected type semiconductor device is asemiconductor device contrived to improve a rated value in a way thatestablishes an inverse parallel connection between electrodes of both ofan IGBT chip and a free wheel diode chip (or FRD chip) by applying apressure to between electrode plates after disposing the IGBT chip andthe FRD chip.

This type of semiconductor device is now described in detail. A chipframe composed of a synthetic resin is attached to respective terminalportions of a plurality of chips, and the chips are arrayed on the sameplane so as to abut on this chip frame each other. A first electrodeplate and a second electrode plate are disposed on both of surface sidesthereof and press-fixed to an electrode of each chip by pressing theelectrode plates against the chip, thereby establishing the electricconnection with reduced loss.

FIG. 8 is a schematic diagram showing a layout of the chips disposed ona disk-shaped heat buffer plate 108 in the multi-chip press-connectedtype semiconductor device. Referring to FIG. 8, respective sectionsrepresent IGBT chips and FRD chips, and there is shown a state of beingattached with a holder that will hereinafter be described.

The layout of the chips in the conventional device illustrated in FIG. 8is that the IGBT chips and the FRD chips are so disposed that chips aredispersed to the greatest possible degree as to be accommodated withinthe disk-shaped heat buffer plate 108 for the purpose of taking anexothermic balance between the case of electrifying only the IGBT chipsand the case of electrifying only the diode chips.

A numerical quantity and the layout of the IGBT chips and the FRD chipscan be arbitrarily selected according to required rating, however, anallocation of the numerical quantity of the chips within one singledevice is set, wherein the number of the IGBT chips is normally largerthan the number of the FRD chips in order to enhance a current cut-offcapability as in the form of the device.

Herein, an IGBT device has twenty-one pieces of layout sections, whereinthirteen sections are given to the IGBT chips, and eight sections aregiven to the FRD chips. Chip layout positions are allocated such thatthe numbers are given sequentially from an upper left to the right sidein FIG. 8, and, when reaching the right end, the subsequent numbers aregiven from the left end in the next row. In this example, the chipnumbers 1, 3, 4, 6, 8, 9, 11, 13, 14, 16, 18, 19 and 21 representtotally thirteen pieces of IGBT chips, and the chip numbers 2, 5, 7, 10,12, 15, 17 and 20 (indicated by hatching) represent totally eight piecesof FRD chips. It can be understood that the IGBT chip and the FRD chipare alternately arranged in each row when paying attention to everyrow-direction.

FIG. 9 is a sectional view taken along the line A–A′ in FIG. 8, showinga structure. The IGBT chips 101 and the FRD chips 102 are mountedrespectively on separation type heat buffer plates 103. In this state, acollector electrode is provided on an upper surface of the IGBT chip101, and a cathode electrode is provided on an upper surface of the FRDchip 102.

Further, a plastic holder 104 for acquiring a chip-to-chip withstandvoltage is fitted into a side terminal portion of each chip, therebypositioning the chip in a normal position. Disposed under each heatbuffer plate 103 is a lower electrode plate 105 including emitterelectrode post portions 105A each assuming a protruded shape matchingwith the heat buffer plate 103. A gate substrate 106 for control voltagedistribution to the gate electrode of the IGBT chip 101, is provided ina space between the emitter electrode post portions, and a resinousmember 107 for fixing the chip is provided above the gate substrate 106.Note that an illustration of a connecting portion between the gatesubstrate 106 and a chip gate pad is omitted for simplicity in FIG. 9.

The heat buffer plate 108 and an upper electrode plate 109, which arecomposed of, e.g., molybdenum, are provided upwardly of the chips 101,102. The heat buffer plate 108 abuts on the collector side of the IGBTchip 101 and on the cathode side of the FRD chip 102, thus connectingthese chips in common.

Then, the upper electrode plate and the lower electrode plate arefastened by screws with a compression spring interposed therebetween.With this configuration, the electrodes of the respective chips areefficiently connected, and the heat radiation is efficiently conducted.

Incidentally, the related patent documents are given as follows:

Japanese Patent Publication No. 3256636

Japanese Patent Application Laid-Open Publication No. 2003-7968

As explained above, in the thus constructed press-connected typesemiconductor device, the number of the IGBT chips is normally setlarger than the number of the FRD chips in order to enhance the currentcut-off capability as in the form of the device. Hence, as the number ofthe FRD chips in one single device is smaller than the number of theIGBT chips, in the case of making an electric current having the samemagnitude conductive thereto, an exothermic quantity of the FRD chip islarger than an exothermic quantity of the IGBT chip. In terms of safety,however, it is difficult to reduce the numerical quantity of the IGBTchips because of a necessity for giving a sufficient margin to thecurrent cut-off capacity assured by the semiconductor device.Consequently, there arises a problem in which a power capacity that canbe handled by the semiconductor device is restricted mainly by a heatresistance of the FRD chip.

SUMMARY OF THE INVENTION

According to the first aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising:

a plurality of active element chips to control an electric currentflowing in one direction;

a plurality of diode chips that transmit the current in a directionopposite to the current transmitting direction of said active elementchip; and

electrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under said plurality ofactive element chips and said plurality of diode chips which areinterposed therebetween;

wherein said diode chips are disposed in all of outermost peripheralchip disposing positions respectively having at least one side which isnot adjacent to other chips and in internal chip disposing positionssurrounded by said outermost peripheral chip disposing positions, and

wherein said diode chips are disposed in said internal chip disposingpositions in order of total number of other chips from smaller that anobserved chip is adjacent to at its side or its vertex.

According to the second aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising:

a plurality of active element chips to control an electric currentflowing in one direction;

a plurality of diode chips that transmit the current in a directionopposite to the current transmitting direction of said active elementchip; and

electrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under said plurality ofactive element chips and said plurality of diode chips being interposedtherebetween;

wherein said active element chips and said diode chips coexist inoutermost peripheral chip disposing positions having at least one siderespectively which is not adjacent to other chips, and

wherein said diode chips are disposed in the outermost peripheral chipdisposing positions in order of total number of other chips from smallerthat an observed chip is adjacent to at its side or its vertex.

According to the third aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising:

a plurality of active element chips to control an electric currentflowing in one direction;

a plurality of diode chips that transmit the current in a directionopposite to the current transmitting direction of said active elementchip;

electrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under said plurality ofactive element chips and said plurality of diode chips being interposedtherebetween;

wherein said diode chips are disposed in all of outermost peripheralchip disposing positions having at least one side respectively which isnot adjacent to other chips and in internal chip disposing positionssurrounded by said outermost peripheral chip positions, and

wherein said diode chips are disposed in the internal chip disposingpositions in order of a heat radiation efficiency from the highest thatis determined by a positional relationship with other chips existing inthe periphery of an observed chip.

According to the fourth aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising:

a plurality of active element chips to control an electric currentflowing in one direction;

a plurality of diode chips that transmit the current in a directionopposite to the current transmitting direction of said active elementchip; and

electrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under said plurality ofactive element chips and said plurality of diode chips being interposedtherebetween;

wherein said active element chips and said diode chips coexist inoutermost peripheral chip disposing positions having at least one siderespectively which is not adjacent to other chips, and

wherein said diode chips are disposed in the outermost peripheral chipdisposing positions in order of a heat radiation efficiency from thehighest that is determined by a positional relationship with other chipsexisting in the periphery of an observed chip.

According to the fifth aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising:

a plurality of active element chips to control an electric currentflowing in one direction;

a plurality of diode chips that transmit the current in a directionopposite to the current transmitting direction of said active elementchip; and

electrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under said plurality ofactive element chips and said plurality of diode chips interposedtherebetween;

wherein said diode chips are pressed by a first post portion serving asa pressing device for said diode chip and serving as a current path andsaid active element chips are pressed by a second post portion servingas a pressing device for said active element chips, the sectional areaof said first post portion being larger than that of said second postportion.

According to the sixth aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising: a multi-chip press-connected type semiconductor devicecomprising: a plurality of active element chips to control an electriccurrent flowing in one direction;

a plurality of diode chips that transmit the current in a directionopposite to the current transmitting direction of said active elementchip, and

electrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under with said pluralityof active element chips and said plurality of diode chips beinginterposed therebetween;

wherein a region between posts that press corresponding to said diodechips is formed shallower than regions in other modes.

According to the seventh aspect of the present invention, there isprovided a multi-chip press-connected type semiconductor devicecomprising:

a plurality of chips;

heat buffer plates abutting on said chips; and

electrode plates for the chips, said electrode plates pressing fromabove and under with said plurality of chips being interposedtherebetween;

wherein a part of said chip positioned in an outermost peripheral chipposition extends outwardly of said heat buffer plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the order of disposing IGBT chips and FRDchips in a first embodiment of the multi-chip press-connected typesemiconductor device according to the present invention;

FIGS. 2A through 2H, 2J through 2N, and 2P through 2R are schematicdiagrams showing a variety of typical modes of a layout relationshipbetween a target chip and chips adjacent thereto;

FIG. 3 is a plan view showing the order of disposing the IGBT chips andthe FRD chips in a second embodiment of the multi-chip press-connectedtype semiconductor device according to the present invention;

FIG. 4 is a sectional view showing a structure of the multi-chippress-connected type semiconductor device in a third embodiment of thepresent invention;

FIG. 5 is a sectional view showing a structure of the multi-chippress-connected type semiconductor device in a fourth embodiment of thepresent invention;

FIG. 6 is a sectional view showing a structure of the multi-chippress-connected type semiconductor device in a fifth embodiment of thepresent invention;

FIG. 7 is a front view showing a positional relationship between a FRDchip 202, a buffer plate 203 and a buffer plate 208;

FIG. 8 is a plan view showing how the IGBT chips and the FRD chips aredisposed in a multi-chip press-connected type semiconductor device inthe prior art; and

FIG. 9 is a sectional view showing a section taken along the line A–A′in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will hereinafter be discussed indepth with reference to the drawings.

First Embodiment

A first embodiment of the present invention will be explained byexemplifying a multi-chip type IGBT device.

In the first embodiment, chips are disposed in order from a peripheralposition exhibiting a high heat radiation efficiency. To be specific,the chips are disposed in order of adjacent chips from less to more interms of observing chip-neighboring states in eight peripheraldirections.

FIG. 1 is a plan view showing how the chips are disposed in the firstembodiment, wherein twenty-one pieces of layout sections are provided inthe same way as in the FIG. 8 illustrating the prior art. Referring toFIG. 1, the layout sections are each given one of alphabets A–D and aregrouped into an A-group (embracing positions 1, 3, 4, 8, 14, 18, 19,21), a B-group (positions 2, 9, 13, 20), a C-group (positions 5, 7, 15,17) and a D-group (positions 6, 10, 11, 12, 16), which represent theorder of the heat radiation efficiency from the highest. Twenty onepieces of chips are disposed in the layout sections respectively.

Accordingly, in the first embodiment, totally eight pieces of diodechips are disposed in the A-group, and totally thirteen pieces of IGBTchips are disposed in the B-, C- and D-groups. This layout, though thesame number of diode chips as in the example of the prior art areprovided, enables an increase in handling power capacity by a scheme ofmore efficient heat radiation of the diode chips.

The heat radiation efficiency will hereinafter be described in detail.The heat radiation efficiency should take into account such a point thatthe heat radiation is hindered if another chip exists in the sectionadjacent to a target layout section, or it is undergone exothermicinfluence from another chip. For instance, if another chip is adjacentat its side to the chip concerned, 1 point is decremented from 6 pointsas a maximum scale, and if adjacent in a diagonal direction at itsvertex (a corner), 0.5 point is decremented therefrom. Based on thisindex, 6 points are given if none of the chips exist in the eightperipheral directions (four sides and four vertexes), and 0 point isgiven if the chips exist in all the peripheral directions, wherein ahigher heat radiation efficiency is exhibited as a higher numeric valueis given.

FIGS. 2A through 2R are schematic diagrams showing a variety of typicalmodes of a layout relationship between the chip concerned and theneighboring chip. Layouts having an enantiomorphic relationship and arotational relationship with the layout illustrated herein areabsolutely equivalent thereto in terms of the heat radiation efficiency.

The followings are the heat radiation efficiencies and explanations ofthe modes of the layout relationships in FIGS. 2A through 2R.

FIG. 2A shows a case in which the chips are adjacent at one vertex, andthe heat radiation efficiency is on the order of 5.5. FIG. 2B shows acase in which the chips are adjacent at one side, and the heat radiationefficiency is 5. FIG. 2C shows a case in which the chips are adjacent atone side and one vertex, and the heat radiation efficiency is 4.5. FIGS.2D and 2E show cases in which the chips are adjacent at two sides, andthe heat radiation efficiency is 4. FIG. 2F shows a case in which thechips are adjacent at one side and two vertexes, and the heat radiationefficiency is 4. FIG. 2G shows a case in which the chips are adjacent attwo sides and one vertex, and the heat radiation efficiency is 3.5. FIG.2H shows a case in which the chips are adjacent at three sides, and theheat radiation efficiency is 3. FIG. 2J shows a case in which the chipsare adjacent at two sides and two vertexes, and the heat radiationefficiency is 3. FIG. 2K shows a case in which the chips are adjacent atthree sides and one vertex, and the heat radiation efficiency is 2.5.FIG. 2L shows a case in which the chips are adjacent at three sides andtwo vertexes, and the heat radiation efficiency is 2. FIG. 2M shows acase in which the chips are adjacent at three sides and three vertexes,and the heat radiation efficiency is 1.5. FIG. 2N shows a case in whichthe chips are adjacent at four sides and two vertexes, and the heatradiation efficiency is 1. FIG. 2P shows a case in which the chips areadjacent at three sides and four vertexes, and the heat radiationefficiency is 1. FIG. 2Q shows a case in which the chips are adjacent atfour sides and three vertexes, and the heat radiation efficiency is 0.5.FIG. 2R shows a case in which the chips are adjacent at four sides andfour vertexes, and the heat radiation efficiency is 0.

Hence, “A” in FIG. 1 corresponds to the case in FIG. 23 wherein thechips are adjacent at two sides and two vertexes, and the heat radiationefficiency is 3. “B” corresponds to the case in FIG. 2L wherein thechips are adjacent at three sides and two vertexes, and the heatradiation efficiency is 2. “C” corresponds to the case in FIG. 2Qwherein the chips are adjacent at four sides and three vertexes, and theheat radiation efficiency is 0.5. “D” corresponds to the case in FIG. 2Rwherein the chips are adjacent at four sides and four vertexes, and theheat radiation efficiency is 0.

Further, on the occasion of laying out the diode chips, the diode chipsare arranged in order of the heat radiation efficiency from the highest.Accordingly, if the diode chips are still left even when the diode chipsare disposed in all the A-group positions, the remaining diode chips aredisposed in the next group positions. The layout scheme is hereafterconducted in the same way.

Moreover, it is required that the diode chips should be set in a layoutexhibiting a high symmetry as the whole device. Therefore, if the numberof diode chips in a certain group is insufficient, the diode chips aresubstantially equally disposed in the position of this group. Forattaining this, it is preferable that the diode chips be disposed sothat centroidal position on the plane where all the diode chips arearrayed as viewed from above, is substantially coincident with acentroidal position on the plane of the whole semiconductor device.

To give one example, if the number of the diode chips is 6, all theeight sections of the A-group are not filled with the diode chips.Hence, in the case of disposing the diode chips at first in the sections1, 3, 19 and 21, it follows that the remaining two diode chips aredisposed in a couple of sections 4 and 18 or a couple of sections 8 and14 so as to make the centroidal position of the diode chips on the planesubstantially coincident with the centroidal position on the plane ofthe whole semiconductor device.

Further, if the number of the diode chips is 10, all the eight sectionsof the A-group are filled with the diode chips, and hence the two diodechips are disposed in any two sections among the four sections of thenext B-group. In this case, however, these two diode chips are disposedselectively in a couple of sections 2 and 20 or a couple of sections 9and 13 so as to similarly make the centroidal position of the diodechips on the plane substanctially coincident with the centroidalposition on the plane of the whole semiconductor device.

Thus, considering the heat radiation efficiency, the diode chips aredisposed at first in the outermost peripheral chip positions in thelayout area. After the outermost peripheral chip positions have beenfilled with the diode chips, the diode chips are arrayed in the internalpositions in the order described above. When the active elements and thediode chips coexist in the outermost peripheral chip positions, itfollows that the diode chips are arrayed in the order described above.

Second Embodiment

FIG. 3 is a plan view illustrating a second embodiment of thesemiconductor device according to the present invention, and shows arelationship between layout sections and respective chips on a heatbuffer disk 208, similarly to FIG. 1.

According to the second embodiment, totally nineteen layout sections aregiven on the whole by way one example, wherein the number of the chipsdisposed in respective rows are 3, 4, 5, 4, 3 from the first row down tothe fifth row, and the chips are arranged in such an offset state that alateral pitch in the neighboring row is shifted by half a chip.

In the second embodiment also, as discussed in the first embodiment, theheat radiation efficiency is obtained in a way that uses, as an index, alength of the side of another chip adjacent to the target layoutsection. Therefore, as shown in FIG. 3, the layout sections are groupedinto A, B, C and D in order of the heat radiation efficiency from thehighest.

These layout sections, as in the first embodiment, the diode chips arearranged in order of the heat radiation efficiency from the highest anddisposed, within the group exhibiting the same heat radiationefficiency, so that the centroidal position of the diode chips getsproximal to the centroidal position of the device.

For instance, supposing that eight pieces of diode chips are providedwhile eleven pieces of IGBT chips are provided in FIG. 3, the number oflayout sections of the A-group exhibiting the best heat radiationefficiency is 6, and therefore, after all the layout sections of thisgroup has been filled with chips, remaining two pieces of chips aredisposed in any two sections among four pieces of layout sections of theB-group. In this case, similarly to what has been described in the firstembodiment, any one of a couple of sections 4 and 6 and a couple ofsections 7 and 13 is selected for ensuring the symmetry.

Note that the pitch is shifted by half a chip in every row in FIG. 3,however, if rotated through 90 degrees, it follows that the pitch isshifted by half a chip in every column, these shifts are equivalent.

The assumption in the first and second embodiments discussed above isthat all the sections take square shapes and may take rectangularshapes. In this case, the heat radiation efficiency can be obtained in away that multiplies by a coefficient corresponding to a length of theside.

Thus, the diode chips are disposed in order of the heat radiationefficiency from the highest in terms of considering the layout situationof other chips in the periphery of the chip concerned, thereby enablingthe improvement of the heat radiation efficiency of the diode to beimproved and also the increase in the power capacity that can be handledby the device.

Note that the offset state occurs in all the neighboring rows in theembodiments discussed herein and may occur in at least one pair ofneighboring rows.

Third Embodiment

FIG. 4 is a sectional view of the multi-chip type IGBT device in a thirdembodiment of the present invention, and shows a section taken along theline A–A′ in FIG. 1. In this area, chip numbers 1 and 3 correspond toFRD chips 202, and a chip number 2 corresponds to an IGBT chip 201.These IGBT chip 201 and FRD chips 202 are respectively mounted onseparation type heat buffer plates 203. A collector electrode isprovided on an upper surface of the IGBT chip 201, while a cathodeelectrode is provided on an upper surface of the FRD chip 202. Further,a plastic holder 204 for acquiring a chip-to-chip withstand voltage isfitted into a side terminal portion of each chips, thereby positioningthe chip in a normal position.

Disposed under each heat buffer plate 203 is a lower electrode plate 205including emitter electrode post portions 205A and 205B each assuming aprotruded shape matching with the heat buffer plate 203. A differentpoint from the conventional structure shown in FIG. 1 is that a width W2of the post portion 205A positioned under the FRD chip 202 is wider thana width W1 of the post portion 205B positioned under the IGBT chip 201.Namely, these widths have a relationship such as W2>W1, and sectionalareas thereof also have a relationship given by S2>S1.

According to such a structure, an area of a heat radiation routeextending from the FRD chip 202 to the lower electrode plate 205increases, and hence a thermal resistance from the diode to the outsideelectrode decreases, whereby an allowable power capacity of the devicecan be augmented.

A gate substrate 206 for control voltage wiring to the gate electrode ofthe IGBT chip 201, is provided in a space between the emitter electrodepost portions, and a resinous member 207 for fixing the chip is providedabove the gate substrate 206. The heat buffer plate 208 and an upperelectrode plate 209, which are composed of, e.g., molybdenum, areprovided upwardly of the chips 201, 202. A preferable connection betweenthe parts is attained by finally performing the pressurization. Thesepoints are the same as those in the multi-chip press-connected typesemiconductor device exemplified by way of the example of the prior art.

The third embodiment is applied to the multi-chip press-connected typesemiconductor device in the first embodiment illustrated in FIG. 1, andcan also be applied to the multi-chip press-connected type semiconductordevice based on the structure in the example of the prior art.

Fourth Embodiment

FIG. 5 is a sectional view showing a structure of the multi-chippress-connected type semiconductor device in a fourth embodiment of thepresent invention, and shows a section taken along the line B–B′ inFIG. 1. In the fourth embodiment, as compared with the third embodimentshown in FIG. 4, the width of each post is fixed, however, theredecreases a height of at least one side among the four sides of aprotruded portion of an internal metal post for connecting the FRD chipby pressure. This structure can be attained by providing none of thegate substrate at that portion.

To describe in depth with reference to FIG. 5, in a lower electrodeplate 210, a downward post 210A of an IGBT chip 201 has a left-sidedheight H1 and a right-sided height H2 lower than H1 in FIG. 5, and adownward post 210B of an FRD chip 202 has a left-sided height H2 and aright-sided height H1. Accordingly, a shallow recessed portion havingthe depth H2 and a deep recessed portion having a depth H1 arealternately formed between those posts.

The shallow recessed portion can be actualized by providing no gatewiring substrate for FRD. A connection of gate wiring to the IGBT may beestablished by use of other posts in an unillustrated area by utilizingother gate wiring. Owing to this structure, the heat radiation routeextending from the FRD chip 202 to the outside of the electrode plate210 is expanded, and the heat resistance from the diode to the outsideelectrode decreases. Therefore, as in the third embodiment, theallowable power capacity of the device can be increased.

Fifth Embodiment

A fifth embodiment of the present invention will be explained referringto FIGS. 1, 6 and 7.

FIG. 1 shows the state in which some portions of the peripheral chipspositioned in the sections 1, 3, 4, 8, 14, 18, 19 and 21 are moreprotruded than the heat buffer plate 208 within the device as viewedfrom the plane but do not abut on the heat buffer plate 208.

FIG. 6 is a front view showing a relationship between the FRD chip 202,a buffer plate 203 and a chip protection resinous member 204. Note thatFIG. 6 shows the structure inverted in the vertical direction asopposite to those in FIGS. 4 and 5 for the convenience's sake.

The FRD chip 202 on which the heat is emitted has a region L1 forobtaining a withstand voltage of the chip peripheral portion and aregion L2 for contributing to the current conduction. Then, the chipprotection resinous member 204 for protecting the periphery of the chipis attached to its peripheral portion. The heat radiation is effectedmainly in the region L2 for contributing to the current conduction, andin fact an anode side of the FRD chip is provided with a heat bufferplate abutting on the region L2. Hence, lengthwise portions of therespective regions L1 at both ends in an entire length (2L1+L2) of thechip do not contribute to the heat radiation so much.

The peripheral potion of the heat buffer plate 208 has hitherto beensurrounded with the resin for holding the buffer plate, and the resin isfixed to a resin 207 for holding the chip. Therefore, if theconventional structure remains unchanged, the chip is unable to extrudefrom the heat buffer plate 208.

According to the fifth embodiment, however, as shown in FIG. 7, a partof the FRD chip is extended beyond a range of the heat buffer plate 208by decreasing, to the greatest possible degree, thickness of theprotection resinous member 211 attached to the peripheral portion of theheat buffer plate 208 and by making an edge of the heat buffer plate 203proximal to an internal edge of the protection resinous member 211.

By taking the structure described above, in an envelope having the samesize or in the device having the heat buffer plate, the size of the chipmounted thereon can be made larger than by the prior art, and thecurrent conduction area can be enlarged, thereby making it possible toincrease the power capacity of the whole device.

Note that the device in which a part of the peripheral chip is extendedoutwardly of the heat buffer plate is not limited to the type in whichto coexist the diode, the active element for the power control such asthe IGBT and the diode for current permission in the reversed direction,and can be similarly applied to a type of being mounted with only theactive elements or only the diode chips.

As discussed above, in the multi-chip press-connected type semiconductordevice of the type wherein there are disposed the plurality of activeelement chips for controlling the one-directionally flowing current andthe plurality of diode chips that transmit the current in the directionopposite to the current transmitting direction of the active elementchip, and the electrode plates of the active element chip and of thediode chip are connected by pressure from above and under, when thediode chips are disposed in all of outermost peripheral chip positionsregion with no-existence of other chips adjacent to at least one side ofa certain chip in a chip disposing region, and when the diode chips aredisposed also in internal layout positions, the diode chips are arrangedin order of a total number of other chips from the smallest that existadjacently to at least one of a side and a vertex of a target diode chipin the internal layout position or in order of a heat radiationefficiency from the highest; and, when the active element chips and thediode chips coexist in the outermost peripheral chip positions, thediode chips existing in the outermost peripheral chip positions arearranged for the next time in order of a total number of other chipsfrom the smallest that exist adjacently to at least one of a side and avertex of a target diode chip or in order of a heat radiation efficiencyfrom the highest. Hence, it follows that the diode elements in thedevice are arranged in the positions in order of the heat radiationefficiency from the highest, thereby making it possible to improve theheat radiation efficiency of the diode and to increase a power capacitythat can be handled by the device higher than by the prior art.

Further, in the multi-chip type semiconductor device, a heat resistancefrom a FRD chip to an outside electrode can be reduced by enlarging anarea of press-connected posts corresponding to the diode chips, anelectric current that can be flowed across the FRD chips can beincreased, and the power capacity of the device can be improved.

Moreover, in the multi-chip press-connected semiconductor device, muchlarger elements can be mounted by extending some portions of the chipsexisting in the outermost peripheral chip positions outwardly of theheat buffer plates, whereby the power capacity of the device can beaugmented.

1. A multi-chip press-connected type semiconductor device comprising: aplurality of active element chips to control an electric current flowingin one direction; a plurality of diode chips that transmit the currentin a direction opposite to the current transmitting direction of saidactive element chip; and electrode plates for said active element chipand for said diode chip, said electrode plates pressing from above andunder said plurality of active element chips and said plurality of diodechips which are interposed therebetween; wherein said diode chips aredisposed in all of outermost peripheral chip disposing positionsrespectively having at least one side which is not adjacent to otherchips and in internal chip disposing positions surrounded by saidoutermost peripheral chip disposing positions, and wherein said diodechips are disposed in said internal chip disposing positions in order oftotal number of other chips from smaller that an observed chip isadjacent to at its side or its vertex.
 2. The multi-chip press-connectedtype semiconductor device according to claim 1, wherein said diode chipsare disposed so that a centroidal position, on the plane, of all of saiddiode chips disposed as viewed from above, is substantially coincidentwith a centroidal position, on the plane, of said whole semiconductordevice.
 3. The multi-chip press-connected type semiconductor deviceaccording to claim 1, wherein said plurality of active element chips andsaid plurality of diode chips are arrayed in matrix so that sides ofsaid diode chips face the sides of the active element chips adjacent toeach other in entire lengths of the chips in a direction of either a rowor a column.
 4. The multi-chip press-connected type semiconductor deviceaccording to claim 1, wherein said plurality of active element chips andsaid plurality of diode chips are so arranged as to be shifted by a halfa chip in at least one pair of adjacent rows or columns.
 5. A multi-chippress-connected type semiconductor device comprising: a plurality ofactive element chips to control an electric current flowing in onedirection; a plurality of diode chips that transmit the current in adirection opposite to the current transmitting direction of said activeelement chip; and electrode plates for said active element chip and forsaid diode chip, said electrode plates pressing from above and undersaid plurality of active element chips and said plurality of diode chipsbeing interposed therebetween; wherein said active element chips andsaid diode chips coexist in outermost peripheral chip disposingpositions having at least one side respectively which is not adjacent toother chips, and wherein said diode chips are disposed in the outermostperipheral chip disposing positions in order of total number of otherchips from smaller that an observed chip is adjacent to at its side orits vertex.
 6. The multi-chip press-connected type semiconductor deviceaccording to claim 5, wherein said diode chips are disposed so that acentroidal position, on the plane, of all of said diode chips disposedas viewed from above, is substantially coincident with a centroidalposition, on the plane, of said whole semiconductor device.
 7. Themulti-chip press-connected type semiconductor device according to claim5, wherein said plurality of active element chips and said plurality ofdiode chips are arrayed in matrix so that sides of said diode chips facethe sides of the active element chips adjacent to each other in theirentire lengths in a direction of either a row or a column.
 8. Themulti-chip press-connected type semiconductor device according to claim5, wherein said plurality of active element chips and said plurality ofdiode chips are so arranged as to be shifted by a half a chip in atleast one pair of adjacent rows or columns.
 9. A multi-chippress-connected type semiconductor device comprising: a plurality ofactive element chips to control an electric current flowing in onedirection; a plurality of diode chips that transmit the current in adirection opposite to the current transmitting direction of said activeelement chip; electrode plates for said active element chip and for saiddiode chip, said electrode plates pressing from above and under saidplurality of active element chips and said plurality of diode chipsbeing interposed therebetween; wherein said diode chips are disposed inall of outermost peripheral chip disposing positions having at least oneside respectively which is not adjacent to other chips and in internalchip disposing positions surrounded by said outermost peripheral chippositions, and wherein said diode chips are disposed in the internalchip disposing positions in order of a heat radiation efficiency fromthe highest that is determined by a positional relationship with otherchips existing in the periphery of an observed chip.
 10. The multi-chippress-connected type semiconductor device according to claim 9, whereinthe heat radiation efficiency is so defined as to become higher as thetotal number of other chips adjacent to the side and the vertex of theobserved chip becomes smaller.
 11. The multi-chip press-connected typesemiconductor device according to claim 9, wherein the heat radiationefficiency is so evaluated as to be weighted smaller in the case ofbeing adjacent to the vertex than in the case of being adjacent to theside.
 12. The multi-chip press-connected type semiconductor deviceaccording to claim 9, wherein said diode chips are disposed so that acentroidal position, on the plane, of all of said diode chips disposedas viewed from above, is substantially coincident with a centroidalposition, on the plane, of said whole semiconductor device.
 13. Themulti-chip press-connected type semiconductor device according to claim9, wherein said plurality of active element chips and said plurality ofdiode chips are arrayed in matrix so that sides of said diode chips facethe sides of the active element chips adjacent to each other in theirentire lengths in a direction of either a row or a column.
 14. Themulti-chip press-connected type semiconductor device according to claim9, wherein said plurality of active element chips and said plurality ofdiode chips are so arranged as to be shifted by a half a chip in atleast one pair of adjacent rows or columns.
 15. A multi-chippress-connected type semiconductor device comprising: a plurality ofactive element chips to control an electric current flowing in onedirection; a plurality of diode chips that transmit the current in adirection opposite to the current transmitting direction of said activeelement chip; and electrode plates for said active element chip and forsaid diode chip, said electrode plates pressing from above and undersaid plurality of active element chips and said plurality of diode chipsbeing interposed therebetween; wherein said active element chips andsaid diode chips coexist in outermost peripheral chip disposingpositions having at least one side respectively which is not adjacent toother chips, and wherein said diode chips are disposed in the outermostperipheral chip disposing positions in order of a heat radiationefficiency from the highest that is determined by a positionalrelationship with other chips existing in the periphery of an observedchip.
 16. The multi-chip press-connected type semiconductor deviceaccording to claim 15, wherein the heat radiation efficiency is sodefined as to become higher as the total number of other chips adjacentto the side and the vertex of the chip becomes smaller.
 17. Themulti-chip press-connected type semiconductor device according to claim15, wherein the heat radiation efficiency is so evaluated as to beweighted smaller in the case of being adjacent to the vertex than in thecase of being adjacent to the side.
 18. The multi-chip press-connectedtype semiconductor device according to claim 15, wherein said diodechips are disposed so that a centroidal position, on the plane, of allof said diode chips disposed as viewed from above, is substantiallycoincident with a centroidal position, on the plane, of said wholesemiconductor device.
 19. The multi-chip press-connected typesemiconductor device according to claim 15, wherein said plurality ofactive element chips and said plurality of diode chips are arrayed inmatrix so that sides of said diode chips face the sides of the activeelement chips adjacent to each other in their entire lengths in adirection of either a row or a column.
 20. The multi-chippress-connected type semiconductor device according to claim 15, whereinsaid plurality of active element chips and said plurality of diode chipsare so arranged as to be shifted by a half a chip in at least one pairof adjacent rows or columns.
 21. A multi-chip press-connected typesemiconductor device comprising: a plurality of active element chips tocontrol an electric current flowing in one direction; a plurality ofdiode chips that transmit the current in a direction opposite to thecurrent transmitting direction of said active element chip; andelectrode plates for said active element chip and for said diode chip,said electrode plates pressing from above and under said plurality ofactive element chips and said plurality of diode chips interposedtherebetween; wherein said diode chips are pressed by a first postportion serving as a pressing device for said diode chip and serving asa current path and said active element chips are pressed by a secondpost portion serving as a pressing device for said active element chips,the sectional area of said first post portion being larger than that ofsaid second post portion.
 22. A multi-chip press-connected typesemiconductor device comprising: a plurality of active element chips tocontrol an electric current flowing in one direction; a plurality ofdiode chips that transmit the current in a direction opposite to thecurrent transmitting direction of said active element chip, and upperand lower electrode plates for said active element chip and for saiddiode chip, said electrode plates pressing from above and under withsaid plurality of active element chips and said plurality of diode chipsbeing interposed therebetween; wherein said diode chips and said activeelement chips are respectively pressed by post portions serving as apressing device, and regions between said post portions are provided insaid lower electrode plate such that a shallow recess portion and a deeprecess portion are arranged alternately.
 23. The multi-chippress-connected type semiconductor device according to claim 22, whereina gate wiring substrate is not provided in said shallow recess portion.24. A multi-chip press-connected type semiconductor device comprising:an array of chips having a set of chips positioned in an outermostperipheral array position; a heat buffer plate abutting on said array ofchips; and electrode plates for the chips, said electrode platespressing from above and under with said array of chips being interposedtherebetween; wherein a part of each chip of a subset of chips of saidset of chips positioned in said outermost peripheral array positionextends outwardly of said heat buffer plate.